Color cinematography



y 1951 H. VON FRAUNHOFER ,5 1,299

COLOR CINEMATOGRAPHY Filed March 7, 1946 Subject Minus Blue Filter Dye Minus Green Fi/terQge Negative Car} l en/// Before Yellow-Dyed Blue-Green Sensilriue Emuls/on Layer EXPOSUFG llinus Green Ancl Blue Dye (Red Filter) Red-Sensifi ive Emulsion Layer Expose And Colour De ue/op I //C, lVgGJtH/e arrIer N a I a 0 Ha I 0f After colour film/ s Blu 01 /011 Values M72275 ?;r$% 5/our Values Deuelopment Green/shYel/ow Images Of The Red Colour Values Print P t Yellow-Dyed Blue-Sensitive fmu/sion Layer Before Orthochromatic Emulsion Layer Exposure Cdl'r/er/ I////////M,//I,/

Colour. De ue/op posit/ye Blue-Green Images 07 The Red Colour Values Oran e-Red [ma es 0f 0 an e-Red Ima es 07 After Colour Minb s Blue Color Values Mi'nul? Green 00/06?" Values ATTORNEYS Patented July 17, 1951 STATES PA-TENT- OFFICE Application March], 1946, SeriaLNo. 652,8I' In Great Britain 3111312351945 The various methods and processes for the. production of'colour, motion pictures maybe classified under two main groups, namely: (1) the Additive typesystems and (2) the Subtractive type processes.

Although the additivetype systems are capable of a remarkably close approximation to the appearance of ,nature, none is, unfortunately, free from fundamental limitations that prevent commercialadoption, nor is there any indication of the direction in which further improvements of a fundamental nature could be made in processes of this type.

The subtractive type processes, especially those of the multi-layer kind, because they representedthe one branch of the art that gave some defrnite hope for future development and improvement, were finally adopted'by the motion picture industry. Of these processes there are several which are givingquite satisfactory service today, but up to the present time, the manner of making of the required colour'separation negatives remains complicated, and, in particular, the printing procedure is complicated and expensive. It is a known iact'that the present processes of colour cinematography are not as simple as the black and white processes and, therefore, they are not suitable incases, such as news-reel films, in'which the elements of time and 'cost of productionare of vital consideration.

My invention concerns .a new process for ma-. terially simplifying colour motion picture proce-. dure, from the making of the required colour separation negatives to the printing of the positives, and, in accordancevwith the invention. I combine the best'features of the additive and sub.':-.-

tractive. principles of colour rendition without;

any of their know-n'shortcomings.

Broadly, therefore, the invention may be said toconsist in a process -f0.r the production of; colour motion pictures. wherein different frames of a negative-film comprising two superimposed layers of emulsion areexposed throughdifferent colour filters in such manner as to effect a three-; colour analysis the two seriesof negative images are developed, difierentially coloured and printed simultaneously on to two differently sensitised layers of. emulsion .comprised ina positive film,

which are then developed andappropriatelycol oured, whereby in projection twoof the component colours are obtained subtractively and the third component by an additive effect.

In carrying out. the .process I may employ .a two-layer monopackor bipack film consisting .of an. orthochromatic and a panchromatic emulsion.

2;. Y In accordance with .my process,. all .',of, .the red; colour. values are recorded the ,usua1 ,.uniior m, density on thepanchromaticemulsion whileth'ei green and blue colour records. are.recorded on.;..

, the :orthochrematic emulsion. in difierential den sities. ascompaned; between the, odd.ancheven frames throughout the entire length. of thefilm In printing such t-wo layerl monopack 01 bipaclpfilm; on to-a suitable double coated, positive, film, the result is (two,sets;of zalternate- .frames,.; namely, the red; colour --val,ues.;.,of the =1 oneslayer. insuperimposition on the greencolour. values oi; he. od framesa i ls rimpo c on e. blue-coloun values ofthe even-, frames Further, this process propqfieslto use S t r: tive method of colouring the positives, by the; conversion of -the successive (green and lolue ecolour: values of the one; layer into an-prange reql series of images and the red colour values of the; other layer into' a series of bluergreen images by either. dye-mordanting; chemical toning; coi our development or by anyother. suitable means;

In accordance; with the general; theory-upon; which thiswprocess is designedzto-groperate, thet deepxshadows-rand" blacln are produced gen; screeniin. the same mannerzas in the,;-sub trac ve-i methods,...that. fist-by the-absorption of; gthfl i light,- by meansqof the;.COmbiI1atiOH --Ofi{the red silver deposits in the areas representing blag thetwo sets of images, namely, red and green and red and blue-while white on the other'hand; is produced by the free'transmission of'lightbythe partial oncomple-te absence of reduced silverdeposits in the" areas representing-whitein the two sets of images;

In accordance with the basic theory underlying this process,, that isby the. slight variation .of the silver deposit inoneirameandlayer from that inthe next.frame -and-. layer, a differential colouring;.is given. to. the transmitted light alter: nately; between the twosets of framesand this produces, in projection, .th'e required additive v.ef-i feet toobtain natural colours ,on. the screen.v

There are, obviouslyvarious, ways in which an integral monopackoi ,bipack negative film. for this purpose may .be produced without departing from the basic principle. underlying this inveng tion, However, ,the; method'l prefer for best results is. as follows;

The integralmonopack. negative is formed by, disposing. on. to the ,celluloid. .carrier a. yellow dyed orthochromaticl emulsion. containing, a. dye, forming; substance of suitable. ,type andcha act'er, as. .for. instance .p-nitrophenylacetonitrile',

On to. this. bluefland greensensitive emulsion layer there is then coated or otherwise disposed a layer of a suitable minus green and blue dye, known to the art as a red-filter. This red-filter dye may be employed in a solution with gelatine or other suitable transparent material.

Finally, there is then coated on to the film a coating of red sensitive emulsion containing a dye forming substance of a suitable type and character, as for instance acetoacet 2,5 dichloroanilide.

The required slight variation of the silver deposit in one frame and layer from that in the next frame and layer to obtain the additive effect desired may be achieved by passing the film through a suitable machine which sprays, wipes, coats or otherwise deposits upon the Celluloid carrier a thin layer of suitable minus'blue filterdyes upon the odd frames of the film. Known examples of such minus blue filter-dyes are tartrazine, rapid filter yellow. Upon the adjacent even frames of the film a deposit of minus green filter-dye such as Rose bengal, rhodamine, is applied. Alternatively, there may be afiixed to the camera, a suitable rotating disc arrangement containing the required filters, thus simplifying the manufacture of the integral monopack or bipack.

Obviously, monopack negatives formed in the above described manner must be exposed through the carrier, but by reversing the order and disposition of the two layers so that the emulsion containin the red sensitizer is nearest to the carrier and the blue-green emulsion furthest away from the carrier, exposure may be made in the usual manner with the emulsion facing the lens.

After exposure, the negative is developed in any suitable normal black and white developer and is then fixed and thoroughly Washed. Thereafter the negative is bleached in a suitable bleach for dye coupling by redevelopment. Such bleach may be a mixture of one ounce (300 grams) of potassium ferricyanide, half an ounce (15.0 grams) of potassium bromide, and tap water to make 32 ounces (1 litre) of solution. The negative is bleached completely in this solution, then washed thoroughly and re-developed in a suitable coupling developer which may be composed as follows:

Sodium sulphite; grams 20.0 Sodium carbonate do 40.0 Potassium bromide do 2.0 di-Ethyl-p-phenylenediamino hydrochloride do .5

Water to make 1 litre The result now is a coloured negative of which all of the red colour records of the top layer have been converted into a series of greenishyellow images while the blue-green colour reco'rds of the lower layer have been turned into a series of magenta coloured images.

Obviously, the choice of the dye forming substance may be varied to obtain any suitable combination of colours for each of the two layers of images representing the blue-green and red colour records respectively.

' Alternatively, instead of the use of dye forming substances in the emulsion, the two layers may be converted into colour by dye-mordanting, chemical toning or any other suitable process of which many are known to the art.

The primary purpose of converting the two series of images, incorporated in the two layers of emulsion of the negative, is to reduce the 4 printing of the positive into a single operation and thus to assure perfect registration of the two images and, therefore, to materially shorten the time of production.

My preferred method for making up of the required positive film is the following:

First a layer of orthochromatic emulsion containing an orange-red dye forming substance, such as' for instance a' suitable combination of o chloroacetoacetanilide and p nitrophenylacetonitrile in the proportion of one-third and two-thirds respectively, is disposed upon the Celluloid carrier.

Thereafter, a yellow dyed blue sensitive emulsion containing a blue-green dye forming substance such as for instance 2,4 dichloro-l-naphtol is coated over the lower layer of the positive film.

The negative film described hereinbefore is then printed in the usual black and white fashion by contact or optically, on to this special positive film after which the positive film receives substantially the same processing as that specified for the negative film. Reference may be had to the accompanying drawing which indicates the course of the process by means of a briefed flow diagram.

It should be understood that the present disclosure is for the purpose of illustration only and it will have been appreciated that regardless of whether an integral monopack or a bipack negative film is adopted for analysis purposes, or any double-coated film is used for printing of the positive, the same basic method is employed, and, therefore, the colour images of the negative or of the positive print in each of the component two layers might be produced by any and every toning, mordanting or colour development or colour coupling process that has ever been suggested or used without departing from the basic principle underlying this process and, therefore, all such modifications and equivalents fall Within the scope of the invention. That is to say, that no matter what method of processing may be used for the type of negative or positive material adopted, in one layer thereof the blue-green colour record of the negative will contain differential silver deposits in alternate frames of the positive and, in the other layer of the positive the red colour record printed from the negative will have a uniform deposit in all frames.

I claim:

A process for the production of colour motion pictures which give the effect of a threecolour analysis by means of a combination of additive and subtractive principles, said process comprising producing in a first layer of a twolayer negative film having a first light-sensitive emulsion layer of at least red sensitivity and a second light-sensitive emulsion layer of only orthochromatic sensitivity a series a consecutive frames each recording uniform density images only of red colour values of a photographed subject, producing in said orthochromatic emulsion second layer of said two layer negative film a first series of alternate frames recording images from said subject only of blue-green colour values of minus blue density and a second series of frames alternating with said first series recording images from said subject only of bluegreen colour values of minus green density, converting the images in the frames of the series of the first layer to greenish-yellow, converting the images in both series of the second layer to magenta, printing in a single operation by means of exposure through both layers of the thus coloured two-layer negative film both layers of a two-layer positive film having an orthochromatic-sensitive emulsion first layer protected by a yellow filter and a blue-sensitive emulsion second layer, colouring the images formed in the first layer of the positive orange-red, and colouring the images formed in the second layer of 10 the positive blue-green.

HANS vON FRAUNHOFER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,278,162 Kelley Sept. 10, 1918 1,954,452 Mannes et al Apr. 10, 1934 1,966,653 Thornton July 17, 1934 1,969,469 Mannes et a1 Aug. "I, 1934 2,001,250 Heymer May 14, 1935 2,059,884 Marines et a1 Nov. 3, 1936 

